1EKX

THE ISOLATED, UNREGULATED CATALYTIC TRIMER OF ASPARTATE TRANSCARBAMOYLASE COMPLEXED WITH BISUBSTRATE ANALOG PALA (N-(PHOSPHONACETYL)-L-ASPARTATE)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.171 
  • R-Value Observed: 0.171 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Binding of bisubstrate analog promotes large structural changes in the unregulated catalytic trimer of aspartate transcarbamoylase: implications for allosteric regulation induced cell migration.

Endrizzi, J.A.Beernink, P.T.Alber, T.Schachman, H.K.

(2000) Proc Natl Acad Sci U S A 97: 5077-5082

  • DOI: 10.1073/pnas.090087197
  • Primary Citation of Related Structures:  
    1EKX

  • PubMed Abstract: 
  • A central problem in understanding enzyme regulation is to define the conformational states that account for allosteric changes in catalytic activity. For Escherichia coli aspartate transcarbamoylase (ATCase; EC) the active, relaxed (R state) holoenz ...

    A central problem in understanding enzyme regulation is to define the conformational states that account for allosteric changes in catalytic activity. For Escherichia coli aspartate transcarbamoylase (ATCase; EC) the active, relaxed (R state) holoenzyme is generally assumed to be represented by the crystal structure of the complex of the holoenzyme with the bisubstrate analog N-phosphonacetyl-L-aspartate (PALA). It is unclear, however, which conformational differences between the unliganded, inactive, taut (T state) holoenzyme and the PALA complex are attributable to localized effects of inhibitor binding as contrasted to the allosteric transition. To define the conformational changes in the isolated, nonallosteric C trimer resulting from the binding of PALA, we determined the 1.95-A resolution crystal structure of the C trimer-PALA complex. In contrast to the free C trimer, the PALA-bound trimer exhibits approximate threefold symmetry. Conformational changes in the C trimer upon PALA binding include ordering of two active site loops and closure of the hinge relating the N- and C-terminal domains. The C trimer-PALA structure closely resembles the liganded C subunits in the PALA-bound holoenzyme. This similarity suggests that the pronounced hinge closure and other changes promoted by PALA binding to the holoenzyme are stabilized by ligand binding. Consequently, the conformational changes attributable to the allosteric transition of the holoenzyme remain to be defined.


    Organizational Affiliation

    Department of Molecular and Cell Biology and Virus Laboratory, University of California, Berkeley, CA 94720-3206, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
ASPARTATE TRANSCARBAMOYLASEABC311Escherichia coliMutation(s): 0 
EC: 2.1.3.2
Find proteins for P0A786 (Escherichia coli (strain K12))
Explore P0A786 
Go to UniProtKB:  P0A786
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
PAL
Query on PAL

Download CCD File 
A, B, C
N-(PHOSPHONACETYL)-L-ASPARTIC ACID
C6 H10 N O8 P
ZZKNRXZVGOYGJT-VKHMYHEASA-N
 Ligand Interaction
CA
Query on CA

Download CCD File 
B, C
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.95 Å
  • R-Value Free: 0.214 
  • R-Value Work: 0.171 
  • R-Value Observed: 0.171 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.12α = 90
b = 82.13β = 90
c = 252.51γ = 90
Software Package:
Software NamePurpose
TNTrefinement
REFMACrefinement
MOSFLMdata reduction
CCP4data scaling
TNTphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2000-05-12
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance